Intravascular papillary endothelial hyperplasia: Olanzapine-induced vascular proliferation?

Intravascular papillary endothelial hyperplasia (Masson's tumor) is a reactive vascular lesion of obscure etiopathogenesis, often seen in the head and neck. Its presentation as a scalp swelling, however, is extremely uncommon. We describe the first report in an adult, being treated for bipolar illness.